Photoluminescence properties of Tb3+ and Eu3+ ions co-doped SrMg2La2W2O12 phosphors for solid state lighting applications

Abstract

• Tb 3+ and Eu 3+ co-doped SrMg 2 La 2 W 2 O 12 phosphors were prepared by melt quench method. • Structure and photoluminescence properties of prepared phosphors were investigated. • Emission color changed with change of dopants' concentration. • CIE color coordinates and T cct values were estimated at different excitations. In this paper, we report a series of Tb 3+ and Eu 3+ activated SrMg 2 La 2 W 2 O 12 phosphors synthesized by the solid state reaction method. The structural and photoluminescence properties have been characterized and analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence and decay measurements. X-ray diffraction pattern confirms that the SrMg 2 La 2 W 2 O 12 powders were well indexed to orthorhombic structure (JCPDS card No. 35-0259). The excitation spectra monitored at 547 and 617 nm consist of a broad band in the region 250–370 nm pertaining to O → W ligand to metal charge transfer transition and several narrow bands related to Tb 3+ and Eu 3+ ions absorptions, respectively. The emission spectra of singly Tb 3+ and Eu 3+ doped SrMg 2 La 2 W 2 O 12 phosphors consist of narrow bands from 4f – 4f emission transitions of 5 D 4 and 5 D 0 excited levels to several lower lying levels of Tb 3+ and Eu 3+ ions, respectively. The emission color of phosphors doped with Tb 3+ and Eu 3+ ions has been changed by varying concentrations and excitation wavelengths to obtain white light emission. The Commission Internationale de L’éclairage (CIE) chromaticity coordinates and correlated color temperatures ( T cct ) show that the SrMg 2 La 2 W 2 O 12 :TbEu phosphors can be tuned to exhibit white light emission ranging from 450 to 750 nm, when they are excited by ultraviolet (UV) light.